Improving cut growth resistance of butadiene-vinyl pyridine rubbery copolymers



Patented Sept. 1 3, 1949 IMPROVING CUT GROWTH RESISTANCE BUTADIENE-VINYL PYRIDINE COPOLYMERS or RUBBERY Bernard 0. Barton, Clifton, N. J., assignor to United States Rubber Company, New York, N. Y., a corporation of New J ersey' P No Drawing. Application April 1,1948,

Serial No. 18,499

9 Claims. (01. 2 60-495) This invention relates to butadiene-vinyl pyridine rubbery copolymers and specifically to improving the out growth resistance of such rubbery copolymers.

Rubbery copolymers of butadiene-1,3 and vinyl pyridine are well known materials, having been described in German Patent No. 695,098 and in U. S. Patent No. 2,402,020. However, vulcanized butadiene-vinyl pyridine copolymers have not exhibited satisfactory out growth resistance with the result that their suitability for many purposes was greatly impaired.

I have now found that thecut growth resistance of butadiene-vinyl pyridine rubbery copolymers can be greatly enhanced by adding thereto, prior to curing, a small amount of a halogenated lower aliphatic saturated monocarboxylic acid. In some cases as little as 0.1 part by weight of the halogenated lower fatty acid per 100 parts by weight of butadiene-vinyl pyridinecopolymer is suificient to show improvement. However, I prefer to employ from 1 to 6 parts by weight of the and vulcanization accelerators. In the formulation of the compound, in accordance with my invention there 'is incorporated a small amount of the halogenated lower fatty acid. The compounding is usually effected on the regular rubber 'niill in the usual manner. The resulting compound isthen shaped in the usual way and vulcanized in accordance with conventional practhose wherein the halogen is chlorine or bromine. The halogen may be substituted on any carbon atom in the alkyl chain connected to the carboxylic acid group. Any number of halogen groups may be substituted on the alkyl chain. Examples of halogenated lower fatty acids which .may be used are: chloroacetic acid, bromoacetic acid, dichloroacetic acid, trichloroacetic acid, alpha-chloropropionic acid, beta-chloropropionic acid, alpha-alphapdichloropropionic acid, alphachloro-n-butyric acid, alpha chloroisobutyric acid, gamma-chloro-n-butyric acid, chlorovaleric acid, chlorocaproic acid, etc. The halogenated lowerfatty acids used-in myinvention are preferably free from substitution with groups other than halogen. I generally use those acids wherein the halogen is substituted on the alpha carbon atom.

From the standpoint of cost and availability, and of high effectiveness in increasing out growth resistance chloroacetic acid is by far the preferred material for use in my invention.

I have found that unhalogenated lower alil phatic saturated monocarboxylic acids are not tice. The resulting vulcanizate exhibits greatly increased out growth resistance over the same 'material made without the halogenated lower fatty acid, and none of its other physical properties are impaired. The practice of my invention does not interfere in any respect withthe conventional compounding and vulcanizing techniques/ in the'p ac i e o my i eat eg- I Pr i to u e capable of producing the marked increase in cut growth resistance of butadiene-vinyl pyridine rubber that is produced by the halogenated acids of my invention. This is illustrated by the examples below.

Any butadiene-vinyl pyridine rubbery copolymer may be used inthe practice of the present invention. I usually employ a rubbery copolymer of butadiene and Z-vinyl pyridine but the vinyl as is wellknown in th e art. Usually from 25 to 75% of butadiene and correspondingly from 75 to 25% of the vinyl pyridine are employed. The polymerization of; these two monomers is conducted in any manner known to the art, aqueous emulsion polymerization generally being used. The method of making the butadiene-vinyl pyridine rubbery copolymer does not constitute per se any part of the present invention.

. The following experiments show the effectiveness of halogenated lower fatty acids in improvcut growth resistance of rubbery butadienevinyl pyridine copolymers. Contrary to the well known retarding effect which acids exert on the curing of natural rubber and GR-S (butadiene- Examples 1 to There was first prepared a maste'r batch having the following composition: I y

' Parts by-tweight made as described in the foregoing examples are without any substantial significance. All of the stocks tested were good stocks. 7

From the foregoing it will be apparent that qthe present-inventiomprovides a simple and economicalmethod of overcominglthe "serious dis- Bu-tadiene-vinyl pyridine copolymer 100 Carbon black- 50 Pine tar 2 Zinc oxide -s....-..., 5 sulfurfi hand... 1 12 Benzylidene dimet'fyldithibcarbamatm 0.5

The-a ids indicated 'imtheionowing :tablewere incor orated witn pcmons cr tne master "batch TL in the proportionsd-ndiated mime table and the resulting stocks were' cused for ao minutes and '60 minutesat 45 p. s.-'-i. steam pressure as indicated. As a control -'(Example 1) thesame tests Werema'deona portion ofth cured" master batch containing no addedacidz chloroacetic acid was used inExampie'z; 1 Eiiarnplesfifl and 5 compare 1 the effectof aceticf'acid; cxali'acid and stearic acid; "respective y-. results were as-indicated advantage of vulcanizates made from rubbery butadiene-vinyl pyridine copolymers, namely their lowv resistance to out growth. Incorporation of thehalogenated lower fatty acids of the present invention into the mix is carried out readilyby standard technique and standard compoundingliarid' vulcanizing equipment are, employed.- Thehtilo'genated lower fatty acids d0. -not have any adverse or deleterious efiect during compounding and vulcanizing orupon the vulcaniz'ed product. The preferred materiahnamely, chloroacetic acid,'is comparatively cheap and is readily available and therefore does not present any problem of unduly increasing the cost of cd olynier mbber products; H 'Hav-ing thus 'd'scribed my invention; 'whatI claim and desirejop tqtectby Letters" Patentds:

- manufacture ofcui ed buta'diene vinyl 1 pyridine t'a'dienevinyl pyridine rubbery "copolymer the cut growth resistance of "which? is substantially 'enit -hanced by curing" -in-the;jpresence .tof'frdm l to 6% bywe'i'ght' based on'-the -'-weight of said'copolymer'of a halogenated lowcrffattyaci'd in admixturetherewitli. Y a r 2. As a new composition?of-inatter, curedbutadiene-yinyl'- pyrid in'eErnbbery 'copolymer the out growth J of which; is substantially enhanced by 1n the table.- 7 3o curing 1n the presenceof from '1 t,o-6% by weight Partsby i Modulus- Cut Growth p 3515 3123: g g j V Strcss'at Resistance. V ."Exemplel Acid-Assam: 1595 parts w 300 fElpu-x ,(Kildc'ycl v of master 1 Steam). 9 't,

. v V v I batch) V w x (p s. 1.

1b i d0.;'. .i 6Q ,1730 60 Chlordsc'etic'ficld'. 1.. 1 2.0 1 3O f' 1675 585" 2.0 r 60 .1950 p515 1.3 30 1950; g 60 1.3 .60'. "2150. 70i 2.8 I .30 .1875..- 135, 2.8 60 2100 "80 6.4 30 1450 '125} Examples 6 to? In Examples 6 to 9 thesamei'master: batch as was used in Examples 1 to 5 was-employed.- With 159.5 partsof this master 'batchthere were incorporated 3 parts of each--oi -alpha-chl0ropropicnic: acid, bromoaceticacid,-anddichloroacetic acid. A comparative run Example 6) contained no acid. All 0f the-stocks :WEPQ vulcanized-under the same cond-i-tions narnely for-60 minutes at pounds of-esteampressure. Thegresults were as follows; v l

Example Numbers'nmnn d hlh I (1 7 8 9 'Gon- 'fialogenated Lower trol Fatty Acids Master Batchlparts) 159'. 5 '159. 5 159. 5 Alpha-chloropropionic Aci 3. 0 Bromoacetic Acid 3.- 0 Dichloroacetic' Acid. T 3.0 Stressat300% Elongat ,800. I 2,175 2,085 2,170

Out Growth Resistance (Kilo- 7 cycles per inch of growth) 40 380 14Q I ,210

1 eta ie saessmteta us materials 75 based ontheweight of said copolymer of enmitaceticacid in.- admixture therewith.-; A a new po tionrof: ma ter, c r

tadiene-yinylpyridinerubberyscopolymerthe cut 1 growth "0t which issubstantially; enhanced by curingin the presenceof from ;1 to -.6'% by weight based on the weightof saidcopoly-mer of alpha: chloropropienic acid in admixture therewith. f 7 4. As a new composition-0f matter; cured butad-iene -vinyl pyridine rubber-ycopolymer the cut growthof: whichvis substantial-ly-enhanced by curing in the presence-of;from--1;to-6 by weight based on the Weight of -said copolymer of dichloroacetic acid in admixture therewith. a

5., As a new compositionpfmatterga vulcanizable: mixture containing a butadiene-vinyl pyrinine rubbery -copol-ymen and from 1 to 6%, by weightbased on. the weight of, said copolymer of a halogenated, lower-fatty .acid, said mixture upon vulcanizationyieldinga-vulcanized rubber having a cut growth resistance which is substantially greater; thanan identical; rubber which does not contain said halogenated lower fatty acid. 7 a 6. The processof:m akingyulcaniz ed butadiene- "1;. Asfa new 'c'ompos'itionofhiatter cured bu! vi widi e nd i msa eh st Qfasl bsterli el increased out growth resistance which comprises forming, a vulcanizable mixture containing butadiene-vinyl pyridine rubbery copolymer and from 1 to 6% by weight based on the weight of said copolymer of a halogenated lower fatty acid, and vulcanizing said mixture.

7. The process of claim 6 wherein said acid is chloroacetic acid.

8. The process of claim 6 wherein said acid is alpha-chloropropionic.

9. The process of claim 6 wherein said acid dichloroacetic acid.

BERNARD C. BARTON.

No references cited. 7 

